Nyx in Hesiod's Theogony - Night is born of Chaos; her offspring are many, and telling. With her brother Erebus, Night gives birth to Aether ("atmosphere") and Hemera ("day"). Later, on her own, Night gives birth to Momus "blame", Ponos "toil", Moros "fate", Thanatos "death", Hypnos "sleep", the Oneiroi "the tribe of dreams", the Hesperides, the Keres and Fates, Nemesis, Apate "deception", Philotes "friendship", Geras "age", and Eris "strife".

In his description of Tartarus, Hesiod says further that Hemera "day", who is now Night's sister rather than daughter, left Tartarus just as Nyx entered it; when Hemera returned, Nyx left. This mirrors the portrayal of Ratri "night" in the Rig-Veda, where she works in close cooperation but also tension with her sister Ushas "dawn".